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I seem to have a fault I have never come across before, admittedly I have limited experience. First of all I tried reforming the electrolytic can, no good, it just got very hot and drew quite a large current. I got a new can from Cricklewood electronics and wired it in. I did no more and plugged the set in through the light limiter.

The bulb did not light up but I got a loud crackling from the speaker followed by what I can only describe as a loud (unaffected by the volume control) rasping tone which then rapidly decreased in frequency. I then switched off the set. There is no smoke or any other alarming sights or sounds. This is all very new to me, any ideas gratefully received. Ric.

Are you certain that you've wired the new electrolytic correctly. Modern dual-can electrolytics do not (AFAIK) have colour coded terminals, so it would be easy to confuse the negative one with one of the positives, although in such a case I would have expected 'fireworks' due to reversed polarity.

Hello livewire, thanks for the reply. First, the can I bought was colour coded, the same as the existing one so that all seems OK. I found a 10MF electrolytic under the chassis that had become detached, and having soldered it back (between the volume control and chassis, C29 on the diagram) my raucous tone disappeared, but still have crackling.

The thing is the diagram I have, sourced from a Swiss member, is for a 4611/4612 set and has quite a few differences from my 4615. The set is dated 1948 and would have not been used for some years, it was found in a loft apparently. Would it be safe to assume that all the smaller electrolytics have deteriorated? and would it be better just to replace them? There is quite a collection of parts from all over the world in the set, a lot of U.S parts, war surplus perhaps? Some of these capacitors are low voltages, I am not sure if I can reform them.

Lastly, and this might seem a silly question to most of you, but can I replace electrolytics with ordinary capacitors of the same capacity and voltage? Ric.

Lastly, and this might seem a silly question to most of you, but can I replace electrolytics with ordinary capacitors of the same capacity and voltage? Ric.

You could, if you could find them in the right value ... But you are rather unlikely to. The point of electrolytic capacitors is to get as many Farads as possible into each cubic metre. Electrolytic capacitors generally start at 470 nF and go all the way up to whole Farads; most film capacitor ranges only go up to 1 μF.

Help! I have replaced all the dubious capacitors, most of which seem to be original. I also replaced a section of wire whose rubber insulation had perished and treated the wave change switch to a dose of servisol.

I have SW, along with the ingenious "Magnifier" which works well, MW has a full range of stations and LW has Radio 4. I have no FM at all. (The wave band selector has the letters PU-UKW, I assume this is FM. Apart from this the set sounds well. Any ideas or suggestions gratefully received.

I think that it's likely that the PU-UKW selector position is implying usage of an external VHF converter giving line-level audio out- I believe that quite a few devices of this nature were available. When the set was built, there may still have been debate/uncertainty as to frequency band, modulation method etc. that was to be used.

Besides, there aren't really enough bottles in the set to make UltraKurzWelle work, other by some rather short-cut and poorly-perfoming jiggery pokery!

Many thanks for the advice/information regarding the FM or not of this set. However, pondering it over last night, whilst trying to get to sleep it occurred to me I had made a fundamental error. Examination of the set proved this was the case. Perhaps there is no FM.

Turretslug may well be correct in that an exterior device of some sort could have been added, hence the UKW part of the PU-UKW. If UKW=Ultrakurzwelle could the PU mean Pick up? there is a socket at the back of the set. I don't know, anyway the SW,MW and LW are all working well so I will return the set to its owner.

Yes, Ric, that "PU-UKW" position is basically to connect the amp/speaker to an external source of your choice. Traditionally, a gramophone pickup (hence the more common "gram" designation on British sets), but in the days when this set was made, a VHF/FM tuner would have been another option, and a way for the marketing department to make an ordinary set seem very up-to-the-minute.

You could always connect a modern personal stereo-type radio to the socket if the owner particularly wants to listen to FM broadcasts.

The construction of your radio has a very Philips look to it. The speaker in a cloth bag and the rectifier standing on top of the mains transformer are very characteristic of Philips designs. Also, the use of two ECH21 valves and an EBL21 to give a full superhet using only 3 valves plus rectifier was a Philips innovation that was also adopted by Tesla and others, see here

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